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November 2020 / 21 in bulk material handling. He's a graduate of École de Technologies Supérieure with a bachelor's in mechanical engineering. Jack D. Hilbert, PE (jack.hilbert@ hatch.com, 610-657-5286) is an expert bulk solids pneumatic conveying consultant for Hatch in Schnecksville, PA. Prior to that, he was the principal consultant for Pneumatic Conveying Consultants. He holds a BS and MS in mechanical engineering from Penn State Univer- sity, State College, PA. He has more than 45 years of experience in the application, design, detailed engi- neering, installation, and operation of pneumatic conveying systems. for the ltration equipment's design and used to calculate the ltration area. To calculate the ltration area, divide each air ow amount (3,000 cfm and 3,600 cfm) by the air-to- cloth ratio of 7.5-to-1 (3,000/7.5 = 400 and 3,600/7.5 = 480). The totals suggest a required ltration area of 400 to 480 square feet for an ade- quate design. However, if the surge factor isn't considered, the ltration area selected could be as low as 160 square feet (1,200/7.5 = 160), but this would very likely lead to some performance- related issues. Conclusion The ltration equipment is an equally important part of the pneumatic conveying system as is the line charger, air supply, or any other component selection. The ltration equipment needs to be designed accordingly to prevent any issues and reworked once the entire system is installed. The next time you're designing or reviewing a new system, take a few moments to place a sharper focus on each step, thinking about how a pneu- matic conveying system is a whole and not individual parts. By incor- porating some of the suggestions made in this article, you can avoid running into later troubles. PBE For further reading Find more information on this topic in articles listed under "Pneumatic conveying" and "Dust collection and dust control" in Powder and Bulk Engineering's article index in the December 2019 issue or the article archive on PBE's website, www.powderbulk.com. Julien Mathieu Morel (julien. mathieu@hatch.com, www.hatch. com) is a bulk material handling engineer for Hatch, based in Mon- treal, QC. He has more than 6 years of experience working exclusively • Cartridge lter type: Use 2-to-1 unless the material being handled requires a dif- ferent ratio Picking the correct ratio is important. If the ratio is too low, you'll end up with an oversized ltration unit, having spent more money than necessary on the equipment and installation for a very conservative design. However, if the ratio is too high, you'll have an undersized ltration unit that can create the type of pneumatic conveying system back pressure previously mentioned, and the plant would likely experience high maintenance with a frequent need to replace the lter elements. Material properties. The last consideration is the material's physical and chemical properties, including temperature, friabil- ity, abrasiveness, toxicity, and any hygroscopic tendencies. Making certain that the material won't have a negative effect on the ltration media is mandatory to ensure the ltration equipment's life expec- tancy. Different ltration media have different resistance to con- tinuous or surge temperature, and material acid, alkali, and abrasion. The ltration media needs to be carefully selected based on the application and the lter media's rating with respect to the individ- ual parameters mentioned. Example Now that the pneumatic conveying system's design consideration in relation to the ltration equipment has been given, let's consider a hypothetical example of a dense- phase pressure system that's designed at 1,200 cfm with a bag- type bin vent lter on the receiving bin. Applying the recommended dense-phase multiplier (surge factor) of 2.5 to 3.0 to 1,200 cfm, an air ow volume ranging from 3,000 to 3,600 cfm needs to be considered Eliminate Bridging and Ratholing Keep your operation running smoothly while maximizing hopper volume with a Carman Vibrating Bin Discharger. Carman's solutions are custom designed for your application. Call us today at 800-456-7560 or email for a FREE brochure. 800-456-7560 www.carmanindustries.com Improve Bin Flow!